Robotic vacuum cleaners are known in the art. In general robotic vacuum cleaners are equipped with drive means in the form of a motor for moving the cleaner across a surface to be cleaned. The robotic vacuum cleaners are further equipped with intelligence in the form of microprocessor(s) and navigation and positioning means for causing an autonomous behaviour such that the robotic vacuum cleaners can freely move around and clean a space in the form of e.g. a room.
In many fields of technology, it is desirable to use robots with an autonomous behaviour such that they freely can move around a space without colliding with possible obstacles.
As an a example, robotic vacuum cleaners exist in the art with the capability of more or less autonomously vacuum cleaning a room in which furniture such as tables and chairs and other obstacles such as walls and stairs are located.
Traditionally, these robotic vacuum cleaners have navigated a room by means of using e.g. ultrasound or light waves or laser beams. Such robotic vacuum cleaners usually clean an area or surface by means of parallel strokes or stripes back and forth.
Traditionally, robotic vacuum cleaners have been arranged with circular-shaped main bodies. Such a robot having co-axial drive wheels at the centre of its body has the advantage that it is easy to control and cannot get stuck since it always can rotate 180° and go back the same way it came. However, the circular-shaped main body makes them unsuitable for cleaning corners or edges where a floor meets a wall since these circular vacuum cleaners due to their shape cannot move into a corner or close enough to a wall, or other objects around which cleaning is required such as e.g. chair legs. An example of a robotic vacuum cleaner aiming at solving this problem is disclosed in WO 03/024292, the main body of which at its rear end is circular-shaped, whereas the front end of the main body is substantially rectangular. This is an improvement over the traditional circular-shaped robotic vacuum cleaners in terms of reaching into corners. Further, sweeping brushes are arranged at a bottom side of the main body and disposed such that they are associated with front corner regions of the rectangular-shaped main body front end.
Sweeping, rotating or even steady brushes may further be arranged eccentrically to an opening in the bottom of the main body. The opening may comprise a nozzle or the like to enhance the ability of the robotic vacuum cleaner to reach out into corners and edges and, in some cases, to extend the range or width of the effective cleaning. The brushes may be positioned on the body of the robotic vacuum cleaner similar to the rotating brushes of a machine that is configured to clean streets and other public areas.
In many cases only one brush is arranged on the body of the robotic vacuum cleaner. When the brush is arranged eccentrically or offset of the opening, either on a left or right side thereof, the cleaning movement of the robotic vacuum cleaner should be adapted accordingly. When a stroke or stripe pattern, in which the robotic vacuum cleaner is moving back and forth from stroke to stroke, is used as a cleaning pattern, debris may be pushed off the actual cleaning pattern and thus the cleaning process may not be proper and neat and may leave some debris behind.
For the reasons above there is a need for good planning of the cleaning process and thus the cleaning pattern that is followed by the robotic vacuum cleaner.